WASHINGTON DC: Ever thought of a mechanism that can prevent you from those ruminating traumatic events of the past?

Researchers from the University of Cambridge in Cambridge, England have identified a key chemical within the 'memory' region of the brain that allows us to suppress unwanted thoughts and explained why people suffer from anxiety, post-traumatic stress disorder (PTSD), depression and schizophrenia.

Professor Michael Anderson said the ability to control one's thought is fundamental to their well-being.

"When this capacity breaks down, it causes some of the most debilitating symptoms of psychiatric diseases: intrusive memories, images, hallucinations, ruminations, and pathological and persistent worries. These are all key symptoms of mental illnesses such as PTSD, schizophrenia, depression, and anxiety," Anderson added.

"We wouldn't be able to survive without controlling our actions," he says.

The findings revealed that the ability to inhibit unwanted thoughts relies on a neurotransmitter -- a chemical within the brain that allows messages to pass between nerve cells -- known as GABA.

GABA is the main 'inhibitory' neurotransmitter in the brain and its release by one nerve cell can suppress activity in other cells to which it is connected.

A region in the front side of the brain known as the prefrontal cortex is plays a key role in controlling our actions. It has recently been shown to play an important role in stopping our thoughts.

The team led by Dr Taylor Schmitz and Anderson used a task known as the 'Think/No-Think' procedure to identify a significant new brain process that enables the prefrontal cortex to successfully inhibit our thoughts.

Using a combination of functional magnetic resonance imaging (fMRI) and magnetic resonance spectroscopy, the researchers were able to observe what was happening within the key regions of the brain as the participants tried to inhibit their thoughts.

The team discovered that GABA concentrations within the hippocampus -- a key area of the brain involved in memory -- predict people's ability to block the retrieval process and prevent thoughts and memories from returning.

"Before, we could only say 'this part of the brain acts on that part', but now we can say which neurotransmitters are likely important -- and as a result, infer the role of inhibitory neurons -- in enabling us to stop unwanted thoughts," it said.

This suggests that the hippocampus is failing to inhibit errant thoughts and memories, which may be manifest as hallucinations.

Therefore, the discoveries found in the latest research could be used to help treat individuals suffering from psychiatric diseases.